Bio 117 : Lecture 11-12

Front 1

Population ecology

Back 1

the study of how and why population size changes over time and the effects that population change has on the population.

Front 2

r =

Back 2

per capita growth rate, b - d

Front 3

N =

Back 3

population size

Front 4

rN =

Back 4

rate of population growth

Front 5

Exponential Growth Equation:

Back 5

(dN/dt) = rN

Front 6

in the exponential growth equation, r is typically considered as a

Back 6

maximum r or rmax

Front 7

Logistic or Sigmoid growth involves three stages

Back 7

i. Initial exponential growth.
ii. Decelerating growth rates.
iii. Fluctuations around some “average” population size, often called K or carrying capacity of the environment.

Front 8

Logistic equation:

Back 8

(dN/dt) = rN((K-N)/K)

Front 9

in the logistic equation N = and K =

Back 9

i. N = current pop. size
ii. K = the highest value that N can take or the “carrying capacity” of the environment

Front 10

in the logistic growth equation, r is typically considered as a

Back 10

relative or rrel
(How an individual can reproduce relative to the influence population size has on the individual)

Front 11

The exponential model doesn’t take into account

Back 11

the limit that resources place on populations

Front 12

Carrying Capacity (K).

Back 12

the point at which the population size is in equilibrium with resources
ii. Or the number of individuals of a species that the environment can support.
iii. Or the number of individuals that can survive in the environment.

Front 13

Demography

Back 13

the study of factors that determine the size and structure of a population over time

Front 14

Demography involves

Back 14

the age classes, sex ratio, rates of immigration and emigration, survivorship, mortality, and fecundity of a population

Front 15

Life tables

Back 15

summarize the probabilities that an individual age class will survive and reproduce in any given year over the individual’s lifetime, based on survivor ship

Front 16

cohort

Back 16

All the individuals that are born at the same time, and are thus represented by an age class

Front 17

Type I survivorship curve:

Back 17

Typified by having a large percentage of survivors throughout much of the individual’s life time, which is followed by a rapid decline in individuals within the cohort. Examples include: humans, and some plants.

Front 18

Type II survivorship curve:

Back 18

Typified by a relatively constant decline in survivorship throughout the life of the species. Examples include: independent birds (although your book just says “birds”), and many perennial plants.

Front 19

Type III survivorship curve:

Back 19

Typified by having a low survivorship (high mortality) early in the life of the organism, followed by a fairly high survivorship throughout the remainder of the lifespan. Examples include: many annual plants, and most invertebrates, fish

Front 20

i. Fecundity

Back 20

the number of offspring an individual can have in its lifetime